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Title

Patch-scale summary data

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Contains data for each 900 square-meter patch (patches were the primary units of analysis in the study). These data are the basis of Figures 1 and 2, and Tables 1 and S1, in the paper. Data include the experimental treatment of each patch; gecko (lizard) abundances and densities in July 2013, March 2014, and July 2014; the number and density of trees per patch; mean tree height and basal circumference; abundance and length of insects (gecko prey) captured in sticky traps within each patch; number and density of elephant damaged trees in each patch; and number of trees in each patch occupied by four different symbiotic acacia-ant species (along with unoccupied trees and trees other than Acacia drepanolobium, which do not have ants).

Contains attribute data for each of 559 unique Acacia drepanolobium trees surveyed in July 2013. These data are the basis for Tables 2 and S2 in the paper. Attributes included are: (A) presence/absence of geckos (0,1); (B) presence/absence of elephant damage (0,1); (C) species of symbiotic ant occupant (categorical, with 6 categories); and (D) tree basal circumference.

Abstract1. Disturbance is a crucial determinant of animal abundance, distribution and community structure in many ecosystems, but the ways in which multiple disturbance types interact remain poorly understood. The effects of multiple-disturbance interactions can be additive, subadditive or super-additive (synergistic). Synergistic effects in particular can accelerate ecological change; thus, characterizing such synergies, the conditions under which they arise, and how long they persist has been identified as a major goal of ecology. 2. We factorially manipulated two principal sources of disturbance in African savannas, fire and elephants, and measured their independent and interactive effects on the numerically dominant vertebrate (the arboreal gekkonid lizard Lygodactylus keniensis) and invertebrate (a guild of symbiotic Acacia ants) animal species in a semi-arid Kenyan savanna. 3. Elephant exclusion alone (minus fire) had negligible effects on gecko density. Fire alone (minus elephants) had negligible effects on gecko density after 4 months, but increased gecko density twofold after 16 months, likely because the decay of fire-damaged woody biomass created refuges and nest sites for geckos. In the presence of elephants, fire increased gecko density nearly threefold within 4 months of the experimental burn; this occurred because fire increased the incidence of elephant damage to trees, which in turn improved microhabitat quality for geckos. However, this synergistic positive effect of fire and elephants attenuated over the ensuing year, such that only the main effect of fire was evident after 16 months. 4. Fire also altered the structure of symbiotic plant-ant assemblages occupying the dominant tree species (Acacia drepanolobium); this influenced gecko habitat selection but did not explain the synergistic effect of fire and elephants. However, fire-driven shifts in plant-ant occupancy may have indirectly mediated this effect by increasing trees' susceptibility to elephant damage. 5. Our findings confirm the importance of fire × elephant interactions in structuring arboreal wildlife populations. Where habitat modification by megaherbivores facilitates co-occurring species, fire may amplify these effects in the short term by increasing the frequency or intensity of herbivory, leading to synergy. In the longer term, tree mortality due to both top kill by fire and toppling by large herbivores may reduce overall microhabitat availability, eliminating the synergy.